The communications industry requires not only high-speed data communication but also reliability in those communications. In terrestrial communications, some of the most common communication links are wire line, radio frequency (RF), fiber optic and free-space optical. Each of these communication links has different relative different strengths, weaknesses and tradeoffs in speed and reliability. Typically, the optical systems have higher communication data rates, speeds or bandwidths, and the wire line, RF and fiber optic links have greater reliability.
Although fiber optic links are capable of both high speed and high reliability, they have the disadvantage of requiring a physical installation of a fiber optic cable as the communication path or media between communication points. A wire line link also requires the physical installation of wires or cables as the communication path or media. In many situations, however, it is impractical, uneconomical or impossible to install physical cable media between communication points. In these situations, the wireless RF and/or free-space optical links must be used.
Free-space optical links transmit a light or laser beam through the atmosphere between an optical transmitter and an optical receiver. The aforementioned US patent application describes an optical transceiver within a mixed fiber and free-space optical communication system. Free-space optical communication systems require a clear line-of-sight path between communication points, since the light or laser beam projects in a straight line between the communication points. The optical beam is subject to degradation by smoke, dust, fog, rain, snow and any other particles in the atmosphere between the communication points. These particles and substances refract or block light beam to the degree that it is not reliably received at the receiving communication point. At times, atmospheric conditions can so severely degrade quality of the light beam between the communication points that the free-space optics can fail to work altogether or that the communication rate is diminished to an unacceptable level.
Wireless RF communication links involve broadcasting an RF signal carrying the communication data between the communication points. Although the typical RF broadcast is capable of transmitting data at a slower rate than an optical signal, the broadcast RF signal is usually more dependable. Broadcast RF signals are not subject to the same degradations from atmospheric conditions that cause free-space optical transmissions to suffer. Although some RF systems, such as microwave systems, do require an unobstructed line-of-sight transmission path, particles and substances in the air do not cause substantial RF signal degradation. Thus, RF communications can operate reliably under conditions where free-space optical transmissions can not operate reliably, thereby providing a greater assurance of accurate and effective data transmission although at a somewhat lesser data transfer rate.
It is with respect to these and other considerations, that the present invention has evolved.